class_docstr: Namespace for datetime related expressions.
docstr: Roll backward to the first day of the month.
  
  Returns
  -------
  Expr
      Expression of data type :class:`Date` or :class:`Datetime`.
  
  Notes
  -----
  If you're coming from pandas, you can think of this as a vectorised version
  of `pandas.tseries.offsets.MonthBegin().rollback(datetime)`.
  
  Examples
  --------
  >>> from datetime import datetime
  >>> df = pl.DataFrame(
  ...     {
  ...         "dates": pl.datetime_range(
  ...             datetime(2000, 1, 15, 2),
  ...             datetime(2000, 12, 15, 2),
  ...             "1mo",
  ...             eager=True,
  ...         )
  ...     }
  ... )
  >>> df.select(pl.col("dates").dt.month_start())
  shape: (12, 1)
  ┌─────────────────────┐
  │ dates               │
  │ ---                 │
  │ datetime[μs]        │
  ╞═════════════════════╡
  │ 2000-01-01 02:00:00 │
  │ 2000-02-01 02:00:00 │
  │ 2000-03-01 02:00:00 │
  │ 2000-04-01 02:00:00 │
  │ …                   │
  │ 2000-09-01 02:00:00 │
  │ 2000-10-01 02:00:00 │
  │ 2000-11-01 02:00:00 │
  │ 2000-12-01 02:00:00 │
  └─────────────────────┘
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code: def month_start(self) -> Expr:
      """
      Roll backward to the first day of the month.
  
      Returns
      -------
      Expr
          Expression of data type :class:`Date` or :class:`Datetime`.
  
      Notes
      -----
      If you're coming from pandas, you can think of this as a vectorised version
      of `pandas.tseries.offsets.MonthBegin().rollback(datetime)`.
  
      Examples
      --------
      >>> from datetime import datetime
      >>> df = pl.DataFrame(
      ...     {
      ...         "dates": pl.datetime_range(
      ...             datetime(2000, 1, 15, 2),
      ...             datetime(2000, 12, 15, 2),
      ...             "1mo",
      ...             eager=True,
      ...         )
      ...     }
      ... )
      >>> df.select(pl.col("dates").dt.month_start())
      shape: (12, 1)
      ┌─────────────────────┐
      │ dates               │
      │ ---                 │
      │ datetime[μs]        │
      ╞═════════════════════╡
      │ 2000-01-01 02:00:00 │
      │ 2000-02-01 02:00:00 │
      │ 2000-03-01 02:00:00 │
      │ 2000-04-01 02:00:00 │
      │ …                   │
      │ 2000-09-01 02:00:00 │
      │ 2000-10-01 02:00:00 │
      │ 2000-11-01 02:00:00 │
      │ 2000-12-01 02:00:00 │
      └─────────────────────┘
      """
      return wrap_expr(self._pyexpr.dt_month_start())
  
imports: from __future__ import annotations
  import datetime
  from typing import TYPE_CHECKING
  import polars._reexport
  from polars import functions
  from polars.datatypes import DTYPE_TEMPORAL_UNITS, Date, Int32
  from polars.utils._parse_expr_input import parse_as_expression
  from polars.utils._wrap import wrap_expr
  from polars.utils.convert import _timedelta_to_pl_duration
  from polars.utils.deprecation import deprecate_renamed_function, deprecate_saturating, issue_deprecation_warning, rename_use_earliest_to_ambiguous
label_desc: Use image node_id 39 for calling the ExprDateTimeNameSpace obj's underlying member method code with example usage: obj.month_start() and returns: wrap_expr