简单说来，就是，对于首参a，查找顺序：

a，&a, &mut a,
*a, *&a, *&mut a,
**a, **&a, **&mut a,
....

【 在 txgx 的大作中提到: 】
: https://doc.rust-lang.org/reference/expressions/method-call-expr.html
: A method call consists of an expression (the receiver) followed by a single dot, an expression path segment, and a parenthesized expression-list. Method calls are resolved to associated methods on specific traits, either statically dispatching to a method
:  if the exact self-type of the left-hand-side is known, or dynamically dispatching if the left-hand-side expression is an indirect trait object.
: ...................
--
FROM 123.120.189.*