'Return `True` if `link` can be added to the scheme.
See also
Scheme.check_connect'

def can_connect(self, link):

    check_type(link, SchemeLink)
    try:
        self.check_connect(link)
        return True
    except (SchemeCycleError, IncompatibleChannelTypeError, SinkChannelError, DuplicatedLinkError):
        return False
