def _text2bool(val):
    """
    Converts strings to True/False depending on the 'truth' expressed by
    the string. If the string can't be converted, the original value
    will be returned.

    See '__true_strings' and '__false_strings' for values considered
    'true' or 'false respectively.

    This is usable as 'converter' for SCons' Variables.
    """
    lval = val.lower()
    if lval in __true_strings: return True
    if lval in __false_strings: return False
    raise ValueError("Invalid value for boolean option: %s" % val)
Converts strings to True/False depending on the 'truth' expressed by
    the string. If the string can't be converted, the original value
    will be returned.

    See '__true_strings' and '__false_strings' for values considered
    'true' or 'false respectively.

    This is usable as 'converter' for SCons' Variables.