def _parse_scalars(scalars):
        """Parse the scalars from the YAML file content to a dictionary of ScalarType(s).
        :return: A dictionary { 'full.scalar.label': ScalarType }
        """
        scalar_dict = {}

        # Scalars are defined in a fixed two-level hierarchy within the definition file.
        # The first level contains the category name, while the second level contains the
        # probe name (e.g. "category.name: probe: ...").
        for category_name in scalars:
            category = scalars[category_name]

            for probe_name in category:
                # We found a scalar type. Go ahead and parse it.
                scalar_definition = category[probe_name]
                # We pass |strict_type_checks=False| as we don't want to do any check
                # server side. This includes skipping the checks for the required keys.
                scalar_info = ScalarType(category_name, probe_name, scalar_definition,
                                         strict_type_checks=False)
                scalar_dict[scalar_info.label] = scalar_info

        return scalar_dict