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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 from_string(cls, prjs):
 """ Turn a PROJ.4 string into a mapping of parameters. Bare parameters like "+no_defs" are given a value of ``True``. All keys are checked against the ``all_proj_keys`` list. Args: prjs (str):
 A PROJ4 string. """

        def parse(v):
            try:
                return int(v)
            except ValueError:
                pass
            try:
                return float(v)
            except ValueError:
                return v

        parts = [o.lstrip('+') for o in prjs.strip().split()]

        items = map(
            lambda kv: len(kv) == 2 and (kv[0], parse(kv[1])) or (kv[0], True),
            (p.split('=') for p in parts))

        return cls({k: v for k, v in items if '+'+k in PROJ4_PARAMS.keys()})