<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def delete_edge(self, source: str, target: str):
 """ Removes an edge if it is in the graph. """

        if self.has_edge(source, target):
            self.remove_edge(source, target)