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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def linestyle(i,a=5,b=3):
    '''
    provide one out of 25 unique combinations of style, color and mark

    use in combination with markevery=a+mod(i,b) to add spaced points,
    here a would be the base spacing that would depend on the data
    density, modulated with the number of lines to be plotted (b)

    Parameters
    ----------
    i : integer
        Number of linestyle combination - there are many....
    a : integer
        Spacing of marks.  The default is 5.
    b : integer
        Modulation in case of plotting many nearby lines.  The default
        is 3.

    Examples
    --------

    >>> plot(x,sin(x),linestyle(7)[0], markevery=linestyle(7)[1])


    (c) 2014 FH
    '''

    lines=['-','--','-.',':']
    points=['v','^','<','>','1','2','3','4','s','p','*','h','H','+','x','D','d','o']
    colors=['b','g','r','c','m','k']
    ls_string = colors[sc.mod(i,6)]+lines[sc.mod(i,4)]+points[sc.mod(i,18)]
    mark_i    = a+sc.mod(i,b)
    return ls_string,int(mark_i)