Merge branch 'release/0.8a14'

# Change log of GraphDot

## 0.8a14 (2021-03-09)

- Minor tweaks to look-ahead rewriter logic.

## 0.8a13 (2021-03-08)

- A new and experimental calling convention to allow evaluations of the

__all__ = ['Graph']

__version__ = '0.8a13'

__version__ = '0.8a14'

__author__ = '''Yu-Hang "Maxin" Tang, Oguz Selvitopi, Chi-Feng Wang,

    Thomas H. Li'''

__maintainer__ = 'Yu-Hang "Maxin" Tang'

    @staticmethod

    def _match_context(tree, s, k, n):

        ptrs = [tree[tree.root] for _ in range(n + 1)]

        for i in range(max(k - n, 0), k):

        for i, loc in enumerate(range(max(k - n, 0), k)):

            for j, p in enumerate(ptrs[:i + 1]):

                if p is not None:

                    try:

                        next, = [c for c in tree.children(p.identifier)

                             if c.tag == s[i]]

                                 if c.tag == s[loc]]

                    except (KeyError, ValueError):

                        next = None

                    ptrs[j] = next