text: """Shared docstrings for preprocessing function parameters.
  """
  
  doc_expr_reps = """\
  layer
      If provided, use ``adata.layers[layer]`` for expression values instead
      of `adata.X`.
  use_raw
      If True, use `adata.raw.X` for expression values instead of `adata.X`.\
  """
  
  doc_obs_qc_args = """\
  qc_vars
      Keys for boolean columns of `.var` which identify variables you could 
      want to control for (e.g. "ERCC" or "mito").
  percent_top
      Which proportions of top genes to cover. If empty or `None` don't
      calculate. Values are considered 1-indexed, `percent_top=[50]` finds
      cumulative proportion to the 50th most expressed gene.\
  """
  
  doc_qc_metric_naming = """\
  expr_type
      Name of kind of values in X.
  var_type
      The kind of thing the variables are.\
  """
  
  doc_obs_qc_returns = """\
  Observation level metrics include:
  
  `total_{var_type}_by_{expr_type}`
      E.g. "total_genes_by_counts". Number of genes with positive counts in a cell.
  `total_{expr_type}`
      E.g. "total_counts". Total number of counts for a cell.
  `pct_{expr_type}_in_top_{n}_{var_type}` - for `n` in `percent_top`
      E.g. "pct_counts_in_top_50_genes". Cumulative percentage of counts
      for 50 most expressed genes in a cell.
  `total_{expr_type}_{qc_var}` - for `qc_var` in `qc_vars`
      E.g. "total_counts_mito". Total number of counts for variabes in
      `qc_vars`.
  `pct_{expr_type}_{qc_var}` - for `qc_var` in `qc_vars`
      E.g. "pct_counts_mito". Proportion of total counts for a cell which
      are mitochondrial.\
  """
  
  doc_var_qc_returns = """\
  Variable level metrics include:
  
  `total_{expr_type}`
      E.g. "total_counts". Sum of counts for a gene.
  `mean_{expr_type}`
      E.g. "mean counts". Mean expression over all cells.
  `n_cells_by_{expr_type}`
      E.g. "n_cells_by_counts". Number of cells this expression is
      measured in.
  `pct_dropout_by_{expr_type}`
      E.g. "pct_dropout_by_counts". Percentage of cells this feature does
      not appear in.\
  """
  
  doc_adata_basic = """\
  adata
      Annotated data matrix.\
  """
  