def __add__(self, other):
F = RFunction()<EOL>for key in self.keys():<EOL><INDENT>F[key] = self[key]<EOL><DEDENT>for key in other.keys():<EOL><INDENT>if key in F.keys():<EOL><INDENT>F[key] += other[key]<EOL><DEDENT>else:<EOL><INDENT>F[key] = other[key]<EOL><DEDENT><DEDENT>return F<EOL>
Vector space operation: Add two real-valued functions