.. efun:: string trim(string s)
  string trim(string s, int where)
  string trim(string s, int where, int ch)
  string trim(string s, int where, string ch)
  :include: <strings.h>

  Remove all leading and trailing characters :arg:`ch` from the string :arg:`s` and return the new string.

  :arg:`ch` may be given as a single character, or a string of characters. If :arg:`ch` is not given, it defaults to the whitespace ``" \t"``.

  :arg:`where` can be used to modify where the characters are removed:

    :macro:`TRIM_LEFT`  (1):      remove the leading characters
    :macro:`TRIM_RIGHT` (2):      remove the trailing characters
    :macro:`TRIM_BOTH`  (3 or 0): remove both leading and trailing characters

  .. usage::

    ::

      trim("   1234   ")                  --> "1234"
      trim("   1234   ", TRIM_RIGHT)      --> "   1234"
      trim("   1234   ", TRIM_BOTH, " 1") --> "234"

  :history 3.2.7 introduced:

  .. seealso:: :efun:`regreplace`