code: def find_tendril(cls, proto, addr):
          
  
          # First, normalize the proto
          proto = proto.lower()
  
          # Now, find and return the tendril
          return cls._tendrils[proto][addr]
docs: Finds the tendril corresponding to the protocol and address
          tuple.  Returns the Tendril object, or raises KeyError if the
          tendril is not tracked.
  
          The address tuple is the tuple of the local address and the
          remote address for the tendril.