       crange string firstExpr lastExpr
              Returns  a range of characters from string starting at the char-
              acter indexed by the expression firstExpr (zero-based) until the
              character indexed by the expression lastExpr.

              If  the  expression firstExpr or lastExpr starts with the string
              end, then end is replaced with the index of the  last  character
              in  the  string.  If the expression starts with len, then len is
              replaced with the length of the string.

              This command is UTF-aware.
