<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _bar(s, align, colors, width=100, vmin=None, vmax=None):
 """ Draw bar chart in dataframe cells. """

        # Get input value range.
        smin = s.min() if vmin is None else vmin
        if isinstance(smin, ABCSeries):
            smin = smin.min()
        smax = s.max() if vmax is None else vmax
        if isinstance(smax, ABCSeries):
            smax = smax.max()
        if align == 'mid':
            smin = min(0, smin)
            smax = max(0, smax)
        elif align == 'zero':
            # For "zero" mode, we want the range to be symmetrical around zero.
            smax = max(abs(smin), abs(smax))
            smin = -smax
        # Transform to percent-range of linear-gradient
        normed = width * (s.values - smin) / (smax - smin + 1e-12)
        zero = -width * smin / (smax - smin + 1e-12)

        def css_bar(start, end, color):
            """
            Generate CSS code to draw a bar from start to end.
            """
            css = 'width: 10em; height: 80%;'
            if end > start:
                css += 'background: linear-gradient(90deg,'
                if start > 0:
                    css += ' transparent {s:.1f}%, {c} {s:.1f}%, '.format(
                        s=start, c=color
                    )
                css += '{c} {e:.1f}%, transparent {e:.1f}%)'.format(
                    e=min(end, width), c=color,
                )
            return css

        def css(x):
            if pd.isna(x):
                return ''

            # avoid deprecated indexing `colors[x > zero]`
            color = colors[1] if x > zero else colors[0]

            if align == 'left':
                return css_bar(0, x, color)
            else:
                return css_bar(min(x, zero), max(x, zero), color)

        if s.ndim == 1:
            return [css(x) for x in normed]
        else:
            return pd.DataFrame(
                [[css(x) for x in row] for row in normed],
                index=s.index, columns=s.columns
            )