code: def _concat_managers_axis0(
      mgrs_indexers, axes: list[Index], copy: bool
  ) -> BlockManager:
      """
      concat_managers specialized to concat_axis=0, with reindexing already
      having been done in _maybe_reindex_columns_na_proxy.
      """
      had_reindexers = {
          i: len(mgrs_indexers[i][1]) > 0
          for i in range(len(mgrs_indexers))
      }
      mgrs_indexers = _maybe_reindex_columns_na_proxy(
          axes, mgrs_indexers
      )
  
      mgrs = [x[0] for x in mgrs_indexers]
  
      offset = 0
      blocks = []
      for i, mgr in enumerate(mgrs):
          # If we already reindexed, then we definitely don't need another copy
          made_copy = had_reindexers[i]
  
          for blk in mgr.blocks:
              if made_copy:
                  nb = blk.copy(deep=False)
              elif copy:
                  nb = blk.copy()
              else:
                  # by slicing instead of copy(deep=False), we get a new array
                  #  object, see test_concat_copy
                  nb = blk.getitem_block(slice(None))
              nb._mgr_locs = nb._mgr_locs.add(offset)
              blocks.append(nb)
  
          offset += len(mgr.items)
  
      result = BlockManager(tuple(blocks), axes)
      return result
  
imports: from __future__ import annotations
  import copy
  import itertools
  from typing import TYPE_CHECKING, Sequence, cast
  import numpy
  from pandas._libs import NaT, internals
  from pandas._libs.missing import NA
  from pandas._typing import ArrayLike, AxisInt, DtypeObj, Manager, Shape
  from pandas.util._decorators import cache_readonly
  from pandas.core.dtypes.astype import astype_array
  from pandas.core.dtypes.cast import ensure_dtype_can_hold_na, find_common_type, np_find_common_type
  from pandas.core.dtypes.common import is_1d_only_ea_dtype, is_dtype_equal, is_scalar, needs_i8_conversion
  from pandas.core.dtypes.concat import concat_compat
  from pandas.core.dtypes.dtypes import DatetimeTZDtype, ExtensionDtype
  from pandas.core.dtypes.missing import is_valid_na_for_dtype, isna, isna_all
  import pandas.core.algorithms
  from pandas.core.arrays import DatetimeArray, ExtensionArray
  from pandas.core.arrays.sparse import SparseDtype
  from pandas.core.construction import ensure_wrapped_if_datetimelike
  from pandas.core.internals.array_manager import ArrayManager, NullArrayProxy
  from pandas.core.internals.blocks import ensure_block_shape, new_block_2d
  from pandas.core.internals.managers import BlockManager
label_desc: Use image node_id 4 for calling a global function with example usage: _concat_managers_axis0(mgrs_indexers, axes, copy) and returns: result