<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def label_figure(axes, n_subplots, time_units, sig_name, sig_units, ylabel,
                 title):
    "Add title, and axes labels"
    if title:
        axes[0].set_title(title)

    # Determine y label
    # Explicit labels take precedence if present. Otherwise, construct labels
    # using signal names and units
    if not ylabel:
        ylabel = []
        # Set default channel and signal names if needed
        if not sig_name:
            sig_name = ['ch_'+str(i) for i in range(n_subplots)]
        if not sig_units:
            sig_units = n_subplots * ['NU']

        ylabel = ['/'.join(pair) for pair in zip(sig_name, sig_units)]

        # If there are annotations with channels outside of signal range
        # put placeholders
        n_missing_labels = n_subplots - len(ylabel)
        if n_missing_labels:
            ylabel = ylabel + ['ch_%d/NU' % i for i in range(len(ylabel),
                                                             n_subplots)]

    for ch in range(n_subplots):
        axes[ch].set_ylabel(ylabel[ch])

    axes[-1].set_xlabel('/'.join(['time', time_units[:-1]]))