class_docstr: Cartesian coordinates with fixed relationship between x and y scales
  
  Parameters
  ----------
  ratio : float
      Desired aspect_ratio (:math:`y/x`) of the panel(s).
  xlim : tuple[float, float]
      Limits for x axis. If None, then they are automatically computed.
  ylim : tuple[float, float]
      Limits for y axis. If None, then they are automatically computed.
  expand : bool
      If `True`, expand the coordinate axes by some factor. If `False`,
      use the limits from the data.
  
  Notes
  -----
  To specify aspect ratio of the visual size for the axes use the
  [](`~plotnine.themes.themeable.aspect_ratio`) themeable.
  
  ```python
  ggplot(data, aes('x', 'y')) + theme(aspect_ratio=0.5)
  ```
  
  When changing the `aspect_ratio` in either way, the `width` of the
  panel remains constant (as derived from the
  :class:`plotnine.themes.themeable.figure_size` themeable) and the
  `height` is altered to achieve desired ratio.
code: def __init__(
      self,
      ratio: float = 1,
      xlim: Optional[TupleFloat2] = None,
      ylim: Optional[TupleFloat2] = None,
      expand: bool = True,
  ):
      super().__init__(xlim=xlim, ylim=ylim, expand=expand)
      self.ratio = ratio
  
imports: from __future__ import annotations
  import typing
  from .coord_cartesian import coord_cartesian
label_desc: Use image node_id 1 to create a new coord_fixed object from inherited base classes: coord_cartesian with example: obj = coord_fixed(ratio, xlim, ylim, expand)