class_docstr: Container class for storing all linkable elements for a metric.
  
  TODO: There are similarities with LinkableSpecSet - consider consolidation.
docstr: Returns a set that only includes path keys that map to a single element.
docstr_tok: ["Returns","a","set","that","only","includes","path","keys","that","map","to","a","single","element","."]
code: def only_unique_path_keys(self) -> LinkableElementSet:
      """Returns a set that only includes path keys that map to a single element."""
      return LinkableElementSet(
          path_key_to_linkable_dimensions={
              path_key: linkable_dimensions
              for path_key, linkable_dimensions in self.path_key_to_linkable_dimensions.items()
              if len(linkable_dimensions) <= 1
          },
          path_key_to_linkable_entities={
              path_key: linkable_entities
              for path_key, linkable_entities in self.path_key_to_linkable_entities.items()
              if len(linkable_entities) <= 1
          },
      )
  
imports: from __future__ import annotations
  import logging
  import time
  from collections import defaultdict
  from dataclasses import dataclass
  from typing import Dict, FrozenSet, List, Optional, Sequence, Set, Tuple
  from dbt_semantic_interfaces.enum_extension import assert_values_exhausted
  from dbt_semantic_interfaces.pretty_print import pformat_big_objects
  from dbt_semantic_interfaces.protocols.dimension import Dimension, DimensionType
  from dbt_semantic_interfaces.protocols.semantic_manifest import SemanticManifest
  from dbt_semantic_interfaces.protocols.semantic_model import SemanticModel
  from dbt_semantic_interfaces.references import DimensionReference, MeasureReference, MetricReference, SemanticModelReference, TimeDimensionReference
  from dbt_semantic_interfaces.type_enums import MetricType
  from dbt_semantic_interfaces.type_enums.date_part import DatePart
  from dbt_semantic_interfaces.type_enums.time_granularity import TimeGranularity
  from metricflow.dataset.dataset import DataSet
  from metricflow.errors.errors import UnknownMetricLinkingError
  from metricflow.model.semantics.linkable_element_properties import LinkableElementProperties
  from metricflow.model.semantics.semantic_model_join_evaluator import SemanticModelJoinEvaluator
  from metricflow.model.semantics.semantic_model_lookup import SemanticModelLookup
  from metricflow.protocols.semantics import SemanticModelAccessor
  from metricflow.specs.specs import DEFAULT_TIME_GRANULARITY, DimensionSpec, EntityReference, EntitySpec, LinkableSpecSet, TimeDimensionSpec
label_desc: Use image node_id 5 for calling the LinkableElementSet obj's underlying member method code with example usage: obj.only_unique_path_keys() and returns: LinkableElementSet