numbers.py have a bug!!
*Created originally on Bitbucket by [4744020502 (eson)](https://bitbucket.org/%7B36a19536-5cff-47b4-8a68-52a2a2771298%7D/)*
```
#!python
def is_date_format(fmt):
if fmt is None:
return False
fmt = fmt.lower()
if any([x in fmt for x in DATE_INDICATORS]):
return not BAD_DATE_RE.search(fmt)
return False
```
```
#!python
if any([x in fmt for x in DATE_INDICATORS]):
return not BAD_DATE_RE.search(fmt)
that lead to incorrect return
```
eg:
fmt = m"M"d"D";@ (m"月"d"日";@ extract from my excel file)
issue