code: def _resize(self, shape, format=None, internalformat=None):
          
          shape = self._normalize_shape(shape)
  
          # Check
          if not self._resizable:
              raise RuntimeError("Texture is not resizable")
  
          # Determine format
          if format is None:
              format = self._formats[shape[-1]]
              # Keep current format if channels match
              if self._format and \
                 self._inv_formats[self._format] == self._inv_formats[format]:
                  format = self._format
          else:
              format = check_enum(format)
  
          if internalformat is None:
              # Keep current internalformat if channels match
              if self._internalformat and \
                 self._inv_internalformats[self._internalformat] == shape[-1]:
                  internalformat = self._internalformat
          else:
  
              internalformat = check_enum(internalformat)
  
          # Check
          if format not in self._inv_formats:
              raise ValueError('Invalid texture format: %r.' % format)
          elif shape[-1] != self._inv_formats[format]:
              raise ValueError('Format does not match with given shape. '
                               '(format expects %d elements, data has %d)' %
                               (self._inv_formats[format], shape[-1]))
          
          if internalformat is None:
              pass
          elif internalformat not in self._inv_internalformats:
              raise ValueError(
                  'Invalid texture internalformat: %r. Allowed formats: %r' 
                  % (internalformat, self._inv_internalformats)
              )
          elif shape[-1] != self._inv_internalformats[internalformat]:
              raise ValueError('Internalformat does not match with given shape.')
  
          # Store and send GLIR command
          self._shape = shape
          self._format = format
          self._internalformat = internalformat
          self._glir.command('SIZE', self._id, self._shape, self._format, 
                             self._internalformat)
docs: Internal method for resize.