diff --git a/script/poetry/iscompatible.py b/script/poetry/iscompatible.py
new file mode 100644
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--- /dev/null
+++ b/script/poetry/iscompatible.py
@@ -0,0 +1,157 @@
+"""
+Python versioning with requirements.txt syntax
+==============================================
+
+:mod:`iscompatible` gives you the power of the pip requirements.txt
+syntax for everyday python packages, modules, classes or arbitrary
+functions.
+
+The requirements.txt syntax allows you to specify inexact matches
+between a set of requirements and a version. For example, let's
+assume that the single package foo-5.6.1 exists on disk. The
+following requirements are all compatible with foo-5.6.1.
+
+===========   =================================================
+Requirement   Description
+===========   =================================================
+foo           any version of foo
+foo>=5        any version of foo, above or equal to 5
+foo>=5.6      any version of foo, above or equal to 5.6
+foo==5.6.1    exact match
+foo>5         foo-5 or greater, including minor and patch
+foo>5, <5.7   foo-5 or greater, but less than foo-5.7
+foo>0, <5.7   any foo version less than foo-5.7
+===========   =================================================
+
+Example:
+    >>> iscompatible("foo>=5", (5, 6, 1))
+    True
+    >>> iscompatible("foo>=5.6.1, <5.7", (5, 0, 0))
+    False
+    >>> MyPlugin = type("MyPlugin", (), {'version': (5, 6, 1)})
+    >>> iscompatible("foo==5.6.1", MyPlugin.version)
+    True
+
+References
+^^^^^^^^^^
+
+- `The requirements file-format`_
+
+.. _The requirements file-format: https://pip.readthedocs.org/en/1.1/requirements.html#the-requirements-file-format
+.. _VCS: https://pip.readthedocs.org/en/1.1/requirements.html#version-control
+.. _extras: http://peak.telecommunity.com/DevCenter/setuptools#declaring-extras-optional-features-with-their-own-dependencies
+
+"""
+
+version_info = (0, 1, 1)
+__version__ = "%s.%s.%s" % version_info
+
+
+import re
+import operator
+
+
+def iscompatible(requirements, version):
+    """Return whether or not `requirements` is compatible with `version`
+
+    Arguments:
+        requirements (str): Requirement to compare, e.g. foo==1.0.1
+        version (tuple): Version to compare against, e.g. (1, 0, 1)
+
+    Example:
+        >>> iscompatible("foo<=1", (0, 9, 0))
+        True
+        >>> iscompatible("foo>=1, <1.3", (1, 2, 0))
+        True
+        >>> iscompatible("foo>=0.9.9", (1, 0, 0))
+        True
+        >>> iscompatible("foo>=1.1, <2.1", (2, 0, 0))
+        True
+        >>> iscompatible("foo==1.0.0", (1, 0, 0))
+        True
+        >>> iscompatible("foo==1.0.0", (1, 0, 1))
+        False
+
+    """
+
+    results = list()
+
+    for operator_string, requirement_string in parse_requirements(requirements):
+        operator = operators[operator_string]
+        required = string_to_tuple(requirement_string)
+        result = operator(version, required)
+
+        results.append(result)
+
+    return all(results)
+
+
+def parse_requirements(line):
+    """Return list of tuples with (operator, version) from `line`
+
+    .. note:: This is a minimal re-implementation of
+        pkg_utils.parse_requirements and doesn't include support
+        for `VCS`_ or `extras`_.
+
+
+    Example:
+        >>> parse_requirements("foo==1.0.0")
+        [('==', '1.0.0')]
+        >>> parse_requirements("foo>=1.1.0")
+        [('>=', '1.1.0')]
+        >>> parse_requirements("foo>=1.1.0, <1.2")
+        [('>=', '1.1.0'), ('<', '1.2')]
+
+
+    """
+
+    LINE_END = re.compile(r"\s*(#.*)?$")
+    DISTRO = re.compile(r"\s*((\w|[-.])+)")
+    VERSION = re.compile(r"\s*(<=?|>=?|==|!=)\s*((\w|[-.])+)")
+    COMMA = re.compile(r"\s*,")
+
+    match = DISTRO.match(line)
+    p = match.end()
+    specs = list()
+
+    while not LINE_END.match(line, p):
+        match = VERSION.match(line, p)
+        if not match:
+            raise ValueError(
+                "Expected version spec in",
+                line, "at", line[p:])
+
+        specs.append(match.group(*(1, 2)))
+        p = match.end()
+
+        match = COMMA.match(line, p)
+        if match:
+            p = match.end()  # Skip comma
+        elif not LINE_END.match(line, p):
+            raise ValueError(
+                "Expected ',' or end-of-list in",
+                line, "at", line[p:])
+
+    return specs
+
+
+def string_to_tuple(version):
+    """Convert version as string to tuple
+
+    Example:
+        >>> string_to_tuple("1.0.0")
+        (1, 0, 0)
+        >>> string_to_tuple("2.5")
+        (2, 5)
+
+    """
+
+    return tuple(map(int, version.split(".")))
+
+
+operators = {"<":   operator.lt,
+             "<=":  operator.le,
+             "==":  operator.eq,
+             "!=":  operator.ne,
+             ">=":  operator.ge,
+             ">":   operator.gt}