Fix type inference for ALLOWED_TYPES.

When using mypy to check the package, it will attempt to infer types
that are not specified.

Currently, mypy is able to understand that constructing a dict from a
Sequence[Tuple[X, Y]] yields a Dict[X, Y], but if we use lists instead
of tuples, mypy doesn't understand and seems to think the result is a
Dict[X, X].

This is probably a bug in mypy, but in any case, using tuples here
rather than lists is more idiomatic and doesn't affect the behavior of
the code.

Author: Benjamin Moody

wfdb/io/record.py

@@ -1661,7 +1661,7 @@ def multi_to_single(self, physical, return_res=64, expanded=False):
 # this library
 ALLOWED_TYPES = dict(
     [
-        [index, _header.FIELD_SPECS.loc[index, "allowed_types"]]
+        (index, _header.FIELD_SPECS.loc[index, "allowed_types"])
         for index in _header.FIELD_SPECS.index
     ]
 )