Return the type of the field in the given type, accounting for field name normalization.

def get_field_type_from_schema(schema_type, field_name):
    """Return the type of the field in the given type, accounting for field name normalization."""
    if field_name == '@class':
        return GraphQLString
    else:
        if field_name not in schema_type.fields:
            raise AssertionError(u'Field {} passed validation but was not present on type '
                                 u'{}'.format(field_name, schema_type))

        # Validation guarantees that the field must exist in the schema.
        return schema_type.fields[field_name].type