docstr: returns shape of given frame
docstr_tok: ["returns","shape","of","given","frame"]
code: def get_shape(self, frame=0):
      """returns shape of given frame"""
      subhdr = self.subheaders[frame]
      x = subhdr["x_dimension"].item()
      y = subhdr["y_dimension"].item()
      z = subhdr["z_dimension"].item()
      return x, y, z
  
imports: import warnings
  from numbers import Integral
  import numpy
  from .arraywriters import make_array_writer
  from .fileslice import canonical_slicers, predict_shape, slice2outax
  from .spatialimages import SpatialHeader, SpatialImage
  from .volumeutils import array_from_file, make_dt_codes, native_code, swapped_code
  from .wrapstruct import WrapStruct
label_desc: Use image node_id 2 for calling the EcatSubHeader obj's underlying member method code with example usage: obj.get_shape(frame) and returns: x,  y,  z