class_docstr: A naming scheme for metrics.
class_docstr_tok: ["A","naming","scheme","for","metrics","."]
code: def input_str(self, instance_spec: InstanceSpec) -> Optional[str]:
      spec_set = InstanceSpecSet.from_specs((instance_spec,))
      names = tuple(spec.element_name for spec in spec_set.metric_specs)
  
      if len(names) != 1:
          raise RuntimeError(
              f"Did not get 1 name for {instance_spec}. Got {names}"
          )
  
      return names[0]
  
file_path: metricflow/metricflow/naming/metric_scheme.py
imports: from __future__ import annotations
  from typing import Optional
  from dbt_semantic_interfaces.references import MetricReference
  from typing_extensions import override
  from metricflow.naming.naming_scheme import QueryItemNamingScheme
  from metricflow.specs.patterns.metric_pattern import MetricSpecPattern
  from metricflow.specs.specs import InstanceSpec, InstanceSpecSet
label_desc: Use image node_id 1 for calling the MetricNamingScheme obj's underlying member method code with example usage: obj.input_str(instance_spec) and returns: names