docstr: The fallback printer.
code: def emptyPrinter(self, expr):
      """
      The fallback printer.
      """
      if isinstance(expr, str):
          return expr
      elif hasattr(expr, "__srepr__"):
          return expr.__srepr__()
      elif hasattr(expr, "args") and hasattr(expr.args, "__iter__"):
          l = []
          for o in expr.args:
              l.append(self._print(o))
          return expr.__class__.__name__ + "(%s)" % ", ".join(l)
      elif hasattr(expr, "__module__") and hasattr(expr, "__name__"):
          return "<'%s.%s'>" % (expr.__module__, expr.__name__)
      else:
          return str(expr)
  
imports: from __future__ import annotations
  from typing import Any
  from sympy.core.function import AppliedUndef
  from sympy.core.mul import Mul
  from mpmath.libmp import repr_dps, to_str
  from .printer import Printer, print_function
label_desc: Use image node_id 2 for calling the ReprPrinter obj's underlying member method code with example usage: obj.emptyPrinter(expr) and returns: expr, expr, unknown, unknown, str