def xml_type(val):
    """Return a type string for writing to an XML file.

    Parameters
    ----------
    val : any type
        The value

    Returns
    -------
    type : str
        The type of the value to insert in the XML file
    """
    try:
        return {str: 'string', int: 'int', bool: 'boolean', float: 'float',
            dict: 'dict', list: 'list', tuple: 'tuple'}[type(val)]
    except KeyError:
        return 'string'
