refactor: bump Sourceror and using updates on Refactorex · elixir-lang/expert@57a50ad

variable "f" does not exist and is being expanded to "f()", please use parentheses to remove the ambiguity or change the variable name

variable "a" is unused (if the variable is not meant to be used, prefix it with an underscore)

variable "b" is unused (if the variable is not meant to be used, prefix it with an underscore)