title: plot regression line, abline
body: <p>I have a plot </p>
  
  <pre><code>plot(wine$AGST ~ wine$Price, xlab="Price", ylab = "AGST", pch = 19)
  </code></pre>
  
  <p>and want to draw a regression line ie </p>
  
  <pre><code>abline(lm(Price ~ AGST, data=wine))
  </code></pre>
  
  <p>but facing error ie </p>
  
  <blockquote>
    <p>abline(mod01)
    Warning messages:
    1: In doTryCatch(return(expr), name, parentenv, handler) :
      "lm" is not a graphical parameter
    2: In doTryCatch(return(expr), name, parentenv, handler) :
      "lm" is not a graphical parameter
    abline(lm(Price ~ AGST, data=wine))
    Warning messages:
    1: In doTryCatch(return(expr), name, parentenv, handler) :
      "lm" is not a graphical parameter
    2: In doTryCatch(return(expr), name, parentenv, handler) :
      "lm" is not a graphical parameter
    abline(lm(Price ~ AGST, data=wine))
    Warning messages:
    1: In doTryCatch(return(expr), name, parentenv, handler) :
      "lm" is not a graphical parameter
    2: In doTryCatch(return(expr), name, parentenv, handler) :
      "lm" is not a graphical parameter</p>
  </blockquote>