'Makes the normal curve(s) for create_distplot().
This is called when curve_type = \'normal\' in create_distplot().
:rtype (list) curve: list of normal curve representations'

def make_normal(self):

    curve = ([None] * self.trace_number)
    mean = ([None] * self.trace_number)
    sd = ([None] * self.trace_number)
    for index in range(self.trace_number):
        (mean[index], sd[index]) = scipy_stats.norm.fit(self.hist_data[index])
        self.curve_x[index] = [(self.start[index] + ((x * (self.end[index] - self.start[index])) / 500)) for x in range(500)]
        self.curve_y[index] = scipy_stats.norm.pdf(self.curve_x[index], loc=mean[index], scale=sd[index])
        if (self.histnorm == ALTERNATIVE_HISTNORM):
            self.curve_y[index] *= self.bin_size[index]
    for index in range(self.trace_number):
        curve[index] = dict(type='scatter', x=self.curve_x[index], y=self.curve_y[index], xaxis='x1', yaxis='y1', mode='lines', name=self.group_labels[index], legendgroup=self.group_labels[index], showlegend=(False if self.show_hist else True), marker=dict(color=self.colors[(index % len(self.colors))]))
    return curve
