def dialectfromstring(s):
    """
    Attempts to convert a string representation of a CSV 
    dialect (as would be read from a file header, for instance) 
    into an actual csv.Dialect object.   
    
    """
    try:
        AST = compiler.parse(s)
    except SyntaxError:
        return
    else:
        try:
            if (len(AST.getChildren()) > 1):
                ST = AST.getChildren()[1]
                if isinstance(ST, Stmt):
                    if isinstance(ST.getChildren()[0], Discard):
                        d = ST.getChildren()[0].asList()[0]
        except (TypeError,AttributeError):
            pass
        else:
            if (isinstance(d,Dict) and (len(d.items) > 0)):
                if all([isctype(i[0], str) for i in d.items]):
                    testd = csv.Sniffer().sniff('a,b,c')
                    if all([n.value in dir(testd) and 
                        isctype(v, type(getattr(testd, n.value))) for (n,v) in 
                                                                      d.items]):
                        D = eval(s)
                        for n in D.keys():
                            setattr(testd, n, D[n])
                        return testd