igcd, ilcm: accept list of integr
Application.nargs should be a tuple in all cases (issue 3741)
Canonicalize nargs (to be a tuple) in Function class
Implement some suggestions on PR#2201
Modify Function classes (nargs: int -> tuple)
Fix tests
Revert "Modify Function classes (nargs: int -> tuple)"

This reverts commit 9528e8917ab5cf2c675403204fb9219102bc5cf2.
Merge branch 'master' into 3741-nargs-as-tuple
Drop nargs specifications from Lambda-derived classes
Merge master
return 1 if gcd is 1
Merge branch 'master' into 3741-nargs-as-tuple
Merge branch 'master' into 3741-nargs-as-tuple
Implement nargs canonicalization in the FunctionClass metaclass
Test nargs canonicalization
Merge branch 'master' into 3741-nargs-as-tuple
Cleanup nargs handling
Merge branch 'master' into 3741-nargs-as-tuple
Merge branch 'master' into 3741-nargs-as-tuple
fix error messages wrt what defines plural

Conflicts:
	sympy/core/function.py