'Returns True if the envelopes are equivalent; can compare against
other Envelopes and 4-tuples.'

def __eq__(self, other):

    if isinstance(other, Envelope):
        return ((self.min_x == other.min_x) and (self.min_y == other.min_y) and (self.max_x == other.max_x) and (self.max_y == other.max_y))
    elif (isinstance(other, tuple) and (len(other) == 4)):
        return ((self.min_x == other[0]) and (self.min_y == other[1]) and (self.max_x == other[2]) and (self.max_y == other[3]))
    else:
        raise OGRException('Equivalence    testing    only    works    with    other    Envelopes.')
