proc checkTag { args } {
    set tag      [lindex $args 0] ;# What we are looking for
    set hexBlock [lindex $args 1] ;# our hexBlock [a2 b3 d4]

    # switch $tag
    #   This checks to see if the tag provided exists within the block given
    # Cases:
    # Tag   # Description                                                 # Result
    #   % | Activate a switch on our hexChar to see if it contains "25" | returns value: 1
    #   _ | Activate a switch on our hexChar to see if it contains "5f" | returns value: 1
    switch $tag {
        "%" { switch $hexBlock { 25 { return 1 } } }
        "_" { switch $hexBlock { 5f { return 1 } } }
    } ;# end switch
} ;# end proc

proc hexHunt { args } {

    set range ""
    set tagKeys ""
    set za 0 ;# This is used as our list index

    # x = index of cursor 1 at first index
    # y = index of cursor 2 at second index
    # z = string length count

    set lines [binary encode hex "This is an example of <b>%_hex_hunt_%</b>"]

    foreach line $lines {
        set list ""
        set string_length [string length $line]

        for { lassign {0 1 0} x y z } {$z < $string_length} {incr z} {
            ##
            lappend list [string range $line $x $y] ;# append our two characters of our hexString
            incr x 2 ; incr y 2                     ;# Increase both of our cursors by two
            switch [string range $line $x $y] { "" { break } } ;# if we than reach the end of our string characters break
                                                                # we do this because our string length is not our character length
            ##
        } ;# end for

        foreach item $list {
        #   puts "is my item a % at index $za | [binary decode hex $item] | $item"
            set hexBlock $item ;# Get our two characters from our hex string

            # switch checkTag "%"
            #   This checks to see if the tag provided exists within the block given
            # Cases:
            #   1       | We have a valid tag, increase our block to the next element, and check if the next element matches _
            #   default | We have a valid tag, decrease our block to the previous element and check if the previous block matches _
            switch [checkTag "%" $hexBlock] {
                1 {
        #           puts "yes! at index $za"
        #           puts "Is my next element an _ at index [expr $za+1] ?"

                    set hexBlock [lindex $list [expr $za +1]] ;# increase our hex character by plus one to check our next element

                    # switch checkTag "_"
                    #   This checks to see if the tag provided exists within the block given
                    # Cases:
                    #   1       | We have a valid tag sequence, return our hexBlock to the previous value, 
                    #             set the index to where we located the tag
                    #   default | The character was not a _ so we now check the previous characters
                    switch [checkTag "_" $hexBlock] {
                        1 {
        #                   puts "it is, so a valid tag match!"
        #                   puts "set our starting range!"
                            # decrease our za index to return to us to previous proper value
                            set hexBlock [lindex $list [expr $za -1]]
                            set locatedAt $za
                            #
                        }
                        default {
        #                   puts "No it's not, what about the previous?"
                            set hexBlock [lindex $list [expr $za -1]] ;# set our hexBlock to the previous index
                            # switch checkTag "_"
                            #   This checks to see if the tag provided exists within the block given
                            # Cases:
                            #   1       | We have a valid tag sequence, return our hexBlock to the previous value
                            #   default | the previous block was not a _
                            switch [checkTag "_" $hexBlock] {
                                1 {
        #                           puts "It is! so a valid match!"
                                    set hexBlock [lindex $list [expr $za +1]]
                                    ###
                                    # switch [llength $locatedAt]
                                    #   This checks to see if we have a starting range
                                    # Cases:
                                    #   0       | we have no starting range | break, as this will end up with malformed results
                                    #   1       | We have a valid tag sequence,
                                    #             appended our tag we've collected
                                    switch [llength $locatedAt] {
                                        0 { puts "We have no starting range" ; break }
                                        1 {
        #                                   puts "append range!" ;
                                            ## append the range of where we located our tag and where we are currently at
        #                                   lappend range $locatedAt $za ;# shows the discovered ranges of our tags
                                            lappend tagKeys [binary decode hex [lrange $list $locatedAt $za]]
                                            set locatedAt "" ;# reset our locatedAt for next loop iteration
                                            ##
                                        }
                                    }
                                }
                                default {
        #                           puts "No it wasn't"
                                    set hexChar [lindex $list [expr $za -1]]
                                }
                            }
                        }
                    }
                }
            } ;# end switch [checkTag "%" $hexBlock]
        incr za
        } ;# end foreach item
        set za 0
    } ;# end foreach line
    puts "Discovered tag: $tagKeys"
} ;# end proc

% hexHunt
Discovered tag: %_hex_hunt_%