human
I wrote the below code

    def err(s):
        'Render    as    an    error    span'
        return '<span    class="inline-error    inline">{0}</span>'.format(s)
    def render_arrow(arrow):
        'Turn    text    arrows    into    pretty    ones'
        if (arrow == '->'):
            return u'\u2192'
        if (arrow == '<->'):
            return u'\u2194'
        return arrow
    def render_expression(ex):
        '\n                                Render    a    chemical    expression--no    arrows.\n                                '
        try:
            return _render_to_html(_get_final_tree(ex))
        except ParseException:
            return err(ex)
    def spanify(s):
        return u'<span    class="math">{0}</span>'.format(s)
    (left, arrow, right) = split_on_arrow(eq)
    if (arrow == ''):
        return spanify(render_expression(left))
    return spanify(((render_expression(left) + render_arrow(arrow)) + render_expression(right)))

What's a good function header?

Here's a good function header?
assistant
#Here's a good function header.

def render_to_html(eq):