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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 element_value_should_be(self, locator, expected, strip=False):
 		"""Verifies the element identified by `locator` has the expected value. 		| *Argument* | *Description* | *Example* | 		| locator | Selenium 2 element locator | id=my_id | 		| expected | expected value | My Name Is Slim Shady | 		| strip | Boolean, determines whether it should strip the field's value before comparison or not | ${True} / ${False} |"""


		self._info("Verifying element '%s' value is '%s'" % (locator, expected))
		
		element = self._element_find(locator, True, True)
		value = element.get_attribute('value')

		if (strip):
			value = value.strip()
		
		if str(value) == expected:
			return
		
		else:
			raise AssertionError("Element '%s' value was not '%s', it was '%s'" % (locator, expected, value))