code: def _single_linkage(*args, **kwargs):
      kwargs["linkage"] = "single"
      return linkage_tree(*args, **kwargs)
  
imports: import warnings
  from heapq import heapify, heappop, heappush, heappushpop
  from numbers import Integral, Real
  import numpy
  from scipy import sparse
  from scipy.sparse.csgraph import connected_components
  from ..base import BaseEstimator, ClassNamePrefixFeaturesOutMixin, ClusterMixin, _fit_context
  from ..metrics import DistanceMetric
  from ..metrics._dist_metrics import METRIC_MAPPING64
  from ..metrics.pairwise import _VALID_METRICS, paired_distances
  from ..utils import check_array
  from ..utils._fast_dict import IntFloatDict
  from ..utils._param_validation import HasMethods, Hidden, Interval, StrOptions, validate_params
  from ..utils.graph import _fix_connected_components
  from ..utils.validation import check_memory
  from .None import _hierarchical_fast
  from ._feature_agglomeration import AgglomerationTransform
label_desc: Use image node_id 7 for calling a global function with example usage: _single_linkage() and returns: linkage_tree