<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def read_version():
 """Read version from the first line starting with digit """

    regex = re.compile('^(?P<number>\d.*?) .*$')

    with open('../CHANGELOG.rst') as f:
        for line in f:
            match = regex.match(line)
            if match:
                return match.group('number')