message: Change describe to use self.get_type
  Summary: The describe method is a bit dubious anyway, but might as well remove the one remaining use of `is_function()`. This test will be basically as good.
diff: pub use crate::values::{error::*, iter::*, layout::*, owned::*, traits::*, types::*, unpack::*};
  use crate::{
  collections::{Hashed, SmallHashResult},
  - values::types::function::FunctionInvoker,
  + values::{function::FUNCTION_TYPE, types::function::FunctionInvoker},
  };
  pub use gazebo::{any::AnyLifetime, cell::ARef};
  use indexmap::Equivalent;
  @@ -380,7 +380,7 @@ impl<'v> Value<'v> {
  /// Plan is to make this return a data type at some point in the future, possibly
  /// move on to `StarlarkValue` and include data from members.
  pub fn describe(self, name: &str) -> String {
  - if self.get_aref().is_function() {
  + if self.get_type() == FUNCTION_TYPE {
  format!("def {}: pass", self.to_repr().replace(" = ...", " = None"))
  } else {
  format!("# {} = {}", name, self.to_repr())
  