class_docstr: A representation of a column as a gather map.
  
  This object augments the column with the information that it
  is valid as a gather map for the specified number of rows with
  the given nullification flag.
  
  Parameters
  ----------
  column
      The data to turn into a column and then verify
  nrows
      The number of rows to verify against
  nullify
      Will the gather map be used nullifying out of bounds
      accesses?
  
  Returns
  -------
  GatherMap
      New object wrapping the column bearing witness to its
      suitability as a gather map for columns with nrows.
  
  Raises
  ------
  TypeError
      If the column is of unsuitable dtype
  IndexError
      If the map is not in bounds.
docstr: Construct a new GatherMap from a column without checks.
  
  Parameters
  ----------
  column
     The column that will be used as a gather map
  nrows
     The number of rows the gather map will be used for
  nullify
     Will the gather map be used nullifying out of bounds
     accesses?
  
  Returns
  -------
  GatherMap
  
  Notes
  -----
  This method asserts, by fiat, that the column is valid.
  Behaviour is undefined if it is not.
code: def from_column_unchecked(
      cls, column: "NumericalColumn", nrows: int, *, nullify: bool
  ) -> Self:
      """Construct a new GatherMap from a column without checks.
  
      Parameters
      ----------
      column
         The column that will be used as a gather map
      nrows
         The number of rows the gather map will be used for
      nullify
         Will the gather map be used nullifying out of bounds
         accesses?
  
      Returns
      -------
      GatherMap
  
      Notes
      -----
      This method asserts, by fiat, that the column is valid.
      Behaviour is undefined if it is not.
      """
      self = cls.__new__(cls)
      self.column = column
      self.nrows = nrows
      self.nullify = nullify
      return self
  
file_path: cudf/python/cudf/cudf/core/copy_types.py
imports: from dataclasses import dataclass
  from typing import TYPE_CHECKING, Any, cast
  from typing_extensions import Self
  import cudf
  import cudf._lib
  from cudf._lib.types import size_type_dtype
label_desc: Use image node_id 2 for calling the GatherMap obj's underlying member method code with example usage: obj.from_column_unchecked(cls, column, nrows) and returns: self