Checks if a meta character is escaped or else warns about it.

		If the meta character has an escape character ('\') preceding it,
		the meta character is escaped. If it does not, a warning is emitted
		that the user should escape it.

		Arguments:
			string (str): The relevant string in which the character was found.
			pos (int): The index of the meta character within the string.

		Returns:
			The possibly escaped string and the next meta match.

def escape_meta(self, string, pos):

		"""
		Checks if a meta character is escaped or else warns about it.

		If the meta character has an escape character ('\') preceding it,
		the meta character is escaped. If it does not, a warning is emitted
		that the user should escape it.

		Arguments:
			string (str): The relevant string in which the character was found.
			pos (int): The index of the meta character within the string.

		Returns:
			The possibly escaped string and the next meta match.
		"""

		# Replace escape character
		if pos > 0 and string[pos - 1] == "\\":
			string = string[:pos - 1] + string[pos:]
		else:
			warnings.warn("Un-escaped meta-character: '{0}' (Escape"
						  " it with a '\\')".format(string[pos]),
						  Warning)
			pos += 1

		meta = self.meta.search(string, pos)

		return string, meta