<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def Add(self, other):
 """Returns a copy of this set with a new element added."""

    new_descriptors = []
    for desc in self.descriptors + other.descriptors:
      if desc not in new_descriptors:
        new_descriptors.append(desc)

    return TypeDescriptorSet(*new_descriptors)