class_docstr: Interface specification for variable type instances.
  
  A :term:`Type` instance is mainly responsible for two things:
  
  - creating `Variable` instances (conventionally, `__call__` does this), and
  
  - filtering a value assigned to a `Variable` so that the value
    conforms to restrictions imposed by the type (also known as
    casting, this is done by `filter`).
class_docstr_tok: ["Interface","specification","for","variable","type","instances",".","A",":","term",":","`","Type","`","instance","is","mainly","responsible","for","two","things",":","-","creating","`","Variable","`","instances","(","conventionally",",","`","__call__","`","does","this",")",",","and","-","filtering","a","value","assigned","to","a","`","Variable","`","so","that","the","value","conforms","to","restrictions","imposed","by","the","type","(","also","known","as","casting",",","this","is","done","by","`","filter","`",")","."]
docstr: Produce a `Variable` that's compatible with both `self` and `var.type`, if possible.
  
  A compatible `Variable` is a `Variable` with a `Type` that's the
  "narrower" of `self` and `var.type`.
  
  If a compatible `Type` cannot be found, this method will return
  ``None``.
docstr_tok: ["Produce","a","`","Variable","`","that","'s","compatible","with","both","`","self","`","and","`","var.type","`",",","if","possible",".","A","compatible","`","Variable","`","is","a","`","Variable","`","with","a","`","Type","`","that","'s","the","''","narrower","''","of","`","self","`","and","`","var.type","`",".","If","a","compatible","`","Type","`","can","not","be","found",",","this","method","will","return","``","None","``","."]
code: def convert_variable(self, var: Variable) -> Optional[Variable]:
      """Produce a `Variable` that's compatible with both `self` and `var.type`, if possible.
  
      A compatible `Variable` is a `Variable` with a `Type` that's the
      "narrower" of `self` and `var.type`.
  
      If a compatible `Type` cannot be found, this method will return
      ``None``.
  
      """
      var_type = var.type
  
      if self.is_super(var_type):
          # `var.type` is at least as specific as `self`, so we return it
          # as-is
          return var
      elif var_type.is_super(self):
          # `var.type` is less specific than `self`, so we need to convert it
          # to `self`'s `Type`.
          #
          # Note that, in this case, `var.type != self`, because equality is
          # covered by the branch above.
          raise NotImplementedError()
  
      return None
  
imports: from abc import abstractmethod
  from typing import Any, Generic, Optional, TypeVar, Union
  from typing_extensions import TypeAlias
  from pytensor.graph import utils
  from pytensor.graph.basic import Constant, Variable
  from pytensor.graph.utils import MetaObject
label_desc: Use image node_id 6 for calling the Type obj's underlying member method code with example usage: obj.convert_variable(var) and returns: None, var