Remove all of the elems from other.

		Raises a ValueError if the multiplicity of any elem in other is greater
		than in self.

def remove_all(self, other):
		"""Remove all of the elems from other.

		Raises a ValueError if the multiplicity of any elem in other is greater
		than in self.
		"""
		if not self.is_superset(other):
			raise ValueError('Passed collection is not a subset of this bag')
		self.discard_all(other)