& foreach()
 
  Syntax: foreach([<object>/]<attribute>,<string>[,<begin>, <end>])
 
  Maps a function onto a string.
 
  Each character in <string> has the user-defined function of the 
  first argument performed on it; the character is passed to the 
  function as %0. The results are concatenated. If <begin> and <end> 
  are specified, only the characters between <begin> and <end> are 
  parsed, other characters are concatenated as they are. This allows 
  a rudimentary form of tokens and speeds up the evaluation greatly 
  if tokenizing is your purpose.
 
  Example:
 
  > &add_one me=[add(%0,1)]
  > say [foreach(add_one, 54321)]
  You say, "65432"
 
  > &add_one me=[add(%0,1)]
  > say [foreach(add_one, This adds #0# to numbers in this 
  string,#,#)]
  You say, "This adds 1 to numbers in this string."