<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _common_prefix(names):
 """Get the common prefix for all names"""

    if not names:
        return ''
    prefix = names[0]
    for name in names:
        i = 0
        while i < len(prefix) and i < len(name) and prefix[i] == name[i]:
            i += 1
        prefix = prefix[:i]
    return prefix