Synopsis:
   $strip(<chars> <text>)
   $pass(<chars> <text>)

Technical:
   Both functions are used to single out a set of characters within a given
   string.  The $strip() function removes all occurrences of the characters,
   while $pass() returns them.

Practical:
   The functions have varying uses.  The $strip() function is often used to
   remove any possibly "dangerous" characters from untrusted input; $pass()
   is convenient for counting the number of times certain characters appear
   in the text.

Returns:
   strip: input text with characters removed
   pass:  input characters found in input text

Examples:
   $strip(aeoiu hello there)            returns "hll thr"
   $pass(aeiou hello there)             returns "eoee"

See Also:
   stripansi(6); tr(6)