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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def has_bom(self, f):
 """Check for UTF8, UTF16, and UTF32 BOMs."""


        content = f.read(4)
        encoding = None
        m = RE_UTF_BOM.match(content)
        if m is not None:
            if m.group(1):
                encoding = 'utf-8-sig'
            elif m.group(2):
                encoding = 'utf-32'
            elif m.group(3):
                encoding = 'utf-32'
            elif m.group(4):
                encoding = 'utf-16'
            elif m.group(5):
                encoding = 'utf-16'
        return encoding