class_docstr: Utility class for performing a group by operation over a lazy DataFrame.
  
  Generated by calling `df.lazy().group_by(...)`.
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docstr: Return the number of rows in each group.
  
  Rows containing null values count towards the total.
  
  Examples
  --------
  >>> lf = pl.LazyFrame(
  ...     {
  ...         "a": ["apple", "apple", "orange"],
  ...         "b": [1, None, 2],
  ...     }
  ... )
  >>> lf.group_by("a").count().collect()  # doctest: +SKIP
  shape: (2, 2)
  ┌────────┬───────┐
  │ a      ┆ count │
  │ ---    ┆ ---   │
  │ str    ┆ u32   │
  ╞════════╪═══════╡
  │ apple  ┆ 2     │
  │ orange ┆ 1     │
  └────────┴───────┘
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code: def count(self) -> LazyFrame:
      """
      Return the number of rows in each group.
  
      Rows containing null values count towards the total.
  
      Examples
      --------
      >>> lf = pl.LazyFrame(
      ...     {
      ...         "a": ["apple", "apple", "orange"],
      ...         "b": [1, None, 2],
      ...     }
      ... )
      >>> lf.group_by("a").count().collect()  # doctest: +SKIP
      shape: (2, 2)
      ┌────────┬───────┐
      │ a      ┆ count │
      │ ---    ┆ ---   │
      │ str    ┆ u32   │
      ╞════════╪═══════╡
      │ apple  ┆ 2     │
      │ orange ┆ 1     │
      └────────┴───────┘
      """
      return self.agg(F.count())
  
imports: from __future__ import annotations
  from typing import TYPE_CHECKING, Callable, Iterable
  from polars import functions
  from polars.utils._parse_expr_input import parse_as_list_of_expressions
  from polars.utils._wrap import wrap_ldf
  from polars.utils.deprecation import deprecate_renamed_function
label_desc: Use image node_id 7 for calling the LazyGroupBy obj's underlying member method code with example usage: obj.count() and returns: self