def calc_efficiency (line_str, the_dict):
    # asserts on the parameters
    assert isinstance(the_dict,dict),\
           'bad parameter, expected a dictionary, got {}'.format(the_dict)
    assert isinstance(line_str,str) and line_str != '', \
           'bad parameter, expected string, got {}'.format(line_str)

    line_str = line_str.strip()
    fields_list = line_str.split(',')
    try:
        first_name = fields_list[1]
    except IndexError:
        print line_str
        print fields_list
    last_name = fields_list[2]

    # mapping fields_list in a line to their particular variable.
    # league is a str, everything else an int
    leag,gp,mins,pts,oreb,dreb,reb,asts,stl,blk,to,pf,fga,fgm,fta,ftm,tpa,tpm = \
     fields_list[3],int(fields_list[4]),int(fields_list[5]),int(fields_list[6]),\
     int(fields_list[7]),int(fields_list[8]),int(fields_list[9]),int(fields_list[10]),\
     int(fields_list[11]),int(fields_list[12]),int(fields_list[13]),\
     int(fields_list[14]),int(fields_list[15]),int(fields_list[16]),\
     int(fields_list[17]),int(fields_list[18]), int(fields_list[19]),\
     int(fields_list[20])

    # gp can't be 0
    assert gp!= 0, '{} {} has no games played'.format(first_name, last_name)

    # need to address this problem!
    # assert last_name+first_name not in the_dict,
    #    'duplicate on name {}'.format(first_name + last_name)

    # calculate the player's efficiency
    efficiency = ((pts+reb+asts+stl+blk)-((fga-fgm)+(fta-ftm)+to))/gp

    the_dict[last_name+first_name] = {'first':first_name, 'last':last_name,\
                            'league':leag,'mins':mins,'gp':gp,'pts':pts,\
                            'oreb':oreb,'dreb':dreb,'reb':reb,'asts':asts,\
                            'stl':stl,'blk':blk,'to':to,'fga':fga,'fgm':fgm,\
                            'fta':fta,'ftm':ftm,'tpa':tpa,'tpm':tpm,\
                            'efficiency':efficiency}


def find_most_efficient(the_dict,how_many):
    '''return list of tuples(efficiency, name) from dictionary
    how_many is number of tuples to gather'''
    # user must implement
    return []

def print_results(lst):
    ''' pretty print the results '''
    print('The top {} players in efficency are'.format(len(lst)))
    print('*'*20)

# main program as a function
# catches bad files
# checks file is correct
# with testing
def main (file_name):
    '''
    >>> main('')
    File named  not found
    >>> main('x')
    File named x not found
    >>> main('player_career.csv')
    The top 10 players in efficency are
    ********************
             Wilt Chamberlain : 41.50
                 Bill Russell : 31.71
              Oscar Robertson : 31.61
                   Bob Pettit : 31.11
          Kareem Abdul-jabbar : 30.93
                   Larry Bird : 29.77
                 Elgin Baylor : 29.74
               Michael Jordan : 29.19
                Magic Johnson : 29.10
              Charles Barkley : 28.16
    '''
    try:
        nba_file = open(file_name)
    except IOError:
        print('File named {} not found'.format(file_name))
    else:
        nba_dict={}
        line_str = nba_file.readline()
        if line_str[0:5]!='ilkid':
            raise IOError('bad file format.')       
        for line_str in nba_file:
            calc_efficiency(line_str,nba_dict)

        results_list = find_most_efficient(nba_dict,10)
        print_results(results_list)
        nba_file.close()

if __name__ == '__main__':
    import doctest
    doctest.testmod()