code: def read_double(fid):
      """Read 64bit float from bti file."""
      return _unpack_simple(fid, ">f8", np.float64)
  
imports: import numpy
  from ..._fiff.utils import read_str
label_desc: Use image node_id 14 for calling a global function with example usage: read_double(fid) and returns: _unpack_simple