title: Missing function: Seperate in R
body: <p>I have my function missing with the correct code. Do you know the root cause? Here is the error</p>
  
  <pre><code>library(dplyr)
  df &lt;- data.frame(x = c(NA, "a.b", "a.d", "b.c"))
  df %&gt;% separate(x, c("A", "B"))
  </code></pre>
  
  <blockquote>
    <p>Error in UseMethod("separate") :    no applicable method for
    'separate' applied to an object of class "data.frame"</p>
  </blockquote>