& rest()
 
  Syntax: replace(<list>, <pos>, <word>[, <sep>])
 
  This function inserts a word into <list> so that the word becomes 
  the <pos>'th element of the list, and the word previously in that 
  position is removed. This means that it appears between the 
  <pos-1>'th and <pos+1>'th elements of the original list, replacing 
  the word at that position. This function may not be used to append 
  a word to a list.
 
  <delim> may be used to specify a delimiter other than a space.
 
  Example:
 
  > say replace(This is a test, 4, quiz)
  You say "This is a quiz"
  > say replace(Yet@Another@Mundane@List, 3, Funky, @)
  You say "Yet@Another@Funky@List"
 
  See Also: extract(), insert(), ldelete()