code: function stripTokens(val, negate, variadic) {
      variadic = escape(variadic || constants_1.VARIADIC_CHAR);
      negate = escape(negate || constants_1.NEGATE_CHAR);
      var argExp = new RegExp(['<', '>', '\\[', '\\]'].join('|'), 'g');
      var noExp = new RegExp('^' + negate);
      var variExp = new RegExp(variadic + '$');
      return expandArgs(val)
          .map(function (v) {
          v = v
              .replace(constants_1.FLAG_EXP, '')
              .replace(noExp, '')
              .replace(argExp, '')
              .replace(variExp, '');
          return v;
      }).join(' ');
  }
docs: Strips all tokens from string.
  
  @example 'install <dir> [filename]' >> 'install dir filename'
  
  @param val the val containing tokens to be stripped.
  @param negate the negation char used.
  @param variadic the variadic char used.