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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 define_symbol(name, open_brace, comma, i, j, close_brace, variables, **kwds):
 r"""Define a nice symbol with matrix indices. rho12(t, x, y, z) """

    if variables is None:
        return Symbol(name+open_brace+str(i+1)+comma+str(j+1) +
                      close_brace, **kwds)
    else:
        return Function(name+open_brace+str(i+1)+comma+str(j+1) +
                        close_brace, **kwds)(*variables)