code: def check_csr(user_items):
      if not isinstance(user_items, scipy.sparse.csr_matrix):
          class_name = user_items.__class__.__name__
          start = time.time()
          user_items = user_items.tocsr()
          warnings.warn(
              f"Method expects CSR input, and was passed {class_name} instead. "
              f"Converting to CSR took {time.time() - start} seconds",
              ParameterWarning,
          )
      return user_items
  
file_path: implicit/implicit/utils.py
imports: import time
  import warnings
  import numpy
  import scipy.sparse
  import threadpoolctl
label_desc: Use image node_id 7 for calling a global function with example usage: check_csr(user_items) and returns: user_items