class_docstr: Create y-axis label
  
  Parameters
  ----------
  ylab :
      y-axis label
class_docstr_tok: ["Create","y-axis","label","Parameters","--","--","--","--","--","ylab",":","y-axis","label"]
code: def __init__(self, ylab: str):
      if ylab is None:
          raise PlotnineError("Arguments to ylab cannot be None")
      self.labels = labels_view(y=ylab)
  
file_path: plotnine/plotnine/labels.py
imports: from __future__ import annotations
  import typing
  from .exceptions import PlotnineError
  from .iapi import labels_view
  from .mapping.aes import SCALED_AESTHETICS, rename_aesthetics
label_desc: Use image node_id 1 to create a new ylab object from inherited base classes: labs with example: obj = ylab(ylab)