code: def check_dtype(dt):
      """Check if dtype is a known dtype."""
      if str(dt) in dtype_rev:
          return True
      elif callable(dt) and str(dt().dtype) in dtype_rev:
          return True
      return False
  
file_path: rasterio/rasterio/dtypes.py
imports: import numpy
  from rasterio.env import GDALVersion
label_desc: Use image node_id 4 for calling a global function with example usage: check_dtype(dt) and returns: False, True, True