def parse_boolean(value):
    """
    Parses strings into booleans using the following mapping (case-sensitive):

    'true'   => True
    'false'  => False
    '1'      => True
    '0'      => False
    """
    if value in ['true', '1']:
        return True
    elif value in ['false', '0']:
        return False
    else:
        raise ValueError("expected 'true' or 'false', got '%s'" % value)
