@staticmethod
def get_arcs(analysis):
    """
        Hit stats for each branch.

        Returns a flat list where every four values represent a branch:
        1. line-number
        2. block-number (not used)
        3. branch-number
        4. hits (we only get 1/0 from coverage.py)
        """
    if not analysis.has_arcs():
        return None
    if not hasattr(analysis, 'branch_lines'):
        branch_lines = analysis._branch_lines()
    else:
        branch_lines = analysis.branch_lines()
    branches = []
    for l1, l2 in analysis.arcs_executed():
        if l1 in branch_lines:
            branches.extend((l1, 0, abs(l2), 1))
    for l1, l2 in analysis.arcs_missing():
        if l1 in branch_lines:
            branches.extend((l1, 0, abs(l2), 0))
    return branches
