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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 int(self, length, name, value=None, align=None):
 """Add an signed integer to template. `length` is given in bytes and `value` is optional. `align` can be used to align the field to longer byte length. Signed integer uses twos-complement with bits numbered in big-endian. Examples: | int | 2 | foo | | int | 2 | foo | 42 | | int | 2 | fourByteFoo | 42 | align=4 | """

        self._add_field(Int(length, name, value, align=align))