code: def computeNumberOfMarkers(inputFileName):
      
      nbLine = 0
      with open(inputFileName, "r") as inputFile:
          nbLine = len(inputFile.readlines())
  
      return nbLine
docs: Count the number of marker (line) in a BIM file.
  
      :param inputFileName: the name of the ``bim`` file.
  
      :type inputFileName: str
  
      :returns: the number of marker in the ``bim`` file.