title: Different colors for different keywords in listing environment doesn't work
body: <p>I've read in severl answers I can use <code>[number]</code> to set different colors for different keywords in listings environment. However, when i try this way doesn't work. Someone can help me? These are my preamble and an small example script:</p>
  <pre><code>\usepackage{color}
  \usepackage[dvipsnames]{xcolor}
  
  \definecolor{gray}{rgb}{0.95,0.95,0.95}
  \definecolor{Green}{rgb}{0.1,0.69,0.1}
  \renewcommand{\lstlistingname}{Codice}
  
  \lstdefinelanguage{Python}
  {
    keywords={from, import, def, return, as, for, if, in, len},
    keywordstyle=\color{Green},
    keywords=[2]{centers}
    keywordstyle=[2]{blue} 
    morecomment=[l]{\#},
    morestring=[b]&quot;,
    alsodigit={-},
    alsoletter={&amp;}
  }
      
  \lstdefinestyle{custompython}{
      language=Python,
      frame=tlrb,
      aboveskip=3mm,
      belowskip=5mm,
      backgroundcolor=\color{gray},
      showstringspaces=true,
      columns=flexible,
      basicstyle={\small\ttfamily},
      numbers=left,
      numberstyle=\tiny\color{orange}\ttfamily,
      numbersep=5pt,
      commentstyle=\color{orange},
      stringstyle=\color{purple},
      commentstyle=\small\color{red}\ttfamily,
      breaklines=false,
      breakatwhitespace=true
      tabsize=5
  }
  
  \begin{lstlisting}[firstnumber=1,language=Python, style=custompython]
  
  from pyLensLib.maputils import map_obj, contour_fit
  
  def getImageEllipticity( img, fsize, f=0.05):
   
      m, cnt = map_obj(img), m.get_contours(lev=f)
      centers, axesList = [], []
      
      return centers
  \end{lstlisting}
  </code></pre>