code: def isboolean(ds):
      """Has a boolean measure
  
      >>> isboolean('bool')
      True
      >>> isboolean('3 * ?bool')
      True
      >>> isboolean('int')
      False
      """
      return launder(ds) in boolean
  
file_path: datashader/datashader/datashape/predicates.py
imports: import numpy
  from .util import collect, dshape
  from .internal_utils import remove
  from .coretypes import DataShape, Fixed, Var, Ellipsis, Record, Unit, date_, datetime_, TypeVar, to_numpy_dtype, Categorical
  from .typesets import floating, boolean
label_desc: Use image node_id 12 for calling a global function with example usage: isboolean(ds) and returns: unknown