<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_default(self, ctx):
 """Given a context variable this calculates the default value."""

        # Otherwise go with the regular default.
        if callable(self.default):
            rv = self.default()
        else:
            rv = self.default
        return self.type_cast_value(ctx, rv)