def swallow(name = None, airspeed = None, coconuts = None):

    """

    >>> swallow(name = "Brian")

    This swallow is called Brian

    >>> swallow(airspeed = 42)

    This swallow is flying at 42 furlongs per fortnight

    >>> swallow(coconuts = 3)

    This swallow is carrying 3 coconuts

    """

    if name is not None:

        print u"This swallow is called", name

    if airspeed is not None:

        print u"This swallow is flying at", airspeed, u"furlongs per fortnight"

    if coconuts is not None:

        print u"This swallow is carrying", coconuts, u"coconuts"