code: def linear_kernel(
      X: ArrayLike, Y: Optional[ArrayLike] = None
  ) -> ArrayLike:
      X, Y = check_pairwise_arrays(X, Y)
      return da.dot(X, Y.T)
  
file_path: dask-ml/dask_ml/metrics/pairwise.py
imports: import warnings
  from typing import Any, Callable, Dict, Optional, Tuple, Union
  import dask.array
  import numpy
  from dask import delayed
  from dask.utils import derived_from
  from sklearn import metrics
  from sklearn.metrics.pairwise import KERNEL_PARAMS
  from .._typing import ArrayLike
  from ..utils import row_norms
label_desc: Use image node_id 5 for calling a global function with example usage: linear_kernel(X, Y) and returns: da