Merge comparisons into fmt in (...) call (#229)

Pleasing the pylint gods.

Author: leouieda

gmt/helpers/decorators.py

@@ -284,7 +284,7 @@ def new_module(*args, **kwargs):
             for arg, fmt in conversions.items():
                 if arg in kwargs:
                     value = kwargs[arg]
-                    issequence = fmt == "sequence" or fmt == "sequence_comma"
+                    issequence = fmt in ("sequence", "sequence_comma")
                     if issequence and is_nonstr_iter(value):
                         kwargs[arg] = separators[fmt].join(
                             "{}".format(item) for item in value