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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 symbol_list(what_list):
    '''
    provide default symbol lists

    Parameters
    ----------
    what_list : string
        String name of symbol lists provided; "list1", "list2",
        "lines1" or "lines2".

    '''
    if what_list is "list1":
        symbol=['ro','bo','ko','go','mo'\
                ,'r-','b-','k-','g-','m-','r--','b--','k--'\
                ,'g--','r1']
        #symbol=['r+','ro','r-']
    elif what_list is "list2":
        symbol=['r-','b--','g-.','k:','md','.','o','v','^','<','>','1','2',\
                '3','4','s','p','*','h','H','+']
    elif what_list is "lines1":
        symbol=['b--','k--','r--','c--','m--','g--','b-','k-','r-','c-','m-','g-','b.','b-.','k-.','r-.','c-.','m-.','g-.','b:','k:','r:','c:','m:','g:']
    elif what_list is "lines2":
        symbol=['g:','r-.','k-','b--','k-.','b+','r:','b-','c--','m--','g--','r-','c-','m-','g-','k-.','c-.','m-.','g-.','k:','r:','c:','m:','b-.','b:']
    return symbol