For debugging purposes, when a method is created it needs to be put
into a "filename".  This filename was generated using `repr(attrs)`
however this meant that the filename could change every time the
program was loaded depending on the whims of repr.  (In particular
free functions and lambdas would include ids)

This solves the problem by changing the name to be <attrs generated
{method} {module}.{qualname}> If it should happen that the name is
taken then -2 will be appended and incremented until a free filename
is found.