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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 copy_file(src_filename, dst_filename):
 """Copies a file from one place to another. Both the source and destination files must exist on the same machine. """

    try:
        with open(src_filename, 'rb') as src_file:
            with open(dst_filename, 'wb') as dst_file:
                while True:
                    buf = src_file.read(BUFFER_SIZE)
                    if len(buf) > 0:
                        dst_file.write(buf)
                    if len(buf) < BUFFER_SIZE:
                        break
        return True
    except:
        return False