code: def all_dtypes(expr):
      """Collect set of all data types used in `expr`.
  
      Parameters
      ----------
      expr : tvm.relay.Expr
          The input expression
  
      Returns
      -------
      ret : Set[String]
          Set of data types used in the expression (e.g., `{'int8', 'int32'}`)
      """
      return set(_ffi_api.all_dtypes(expr))
  
imports: from ...ir import IRModule
  from ...relay import transform, build_module
  from ...runtime.ndarray import cpu
  from .None import _ffi_api
  from .feature import Feature
label_desc: Use image node_id 12 for calling a global function with example usage: all_dtypes(expr) and returns: set