title: Lambda calculus predecessor function reduction steps
body: <p>I am getting stuck with the Wikipedia description of the predecessor function in lambda calculus.</p>
  <p>What Wikipedia says is the following:</p>
  <pre><code>PRED := λn.λf.λx. n (λg.λh. h (g f)) (λu.x) (λu.u)
  </code></pre>
  <p>Can someone explain reduction processes step-by-step?</p>
  <p>Thanks.</p>