Add backend to cellxgene repo

backend/app/driver/driver.py

@@ -0,0 +1,57 @@
+from abc import ABC, abstractmethod
+
+class CXGDriver(metaclass=abc.ABCMeta):
+
+	def __init__(self, data, schema=None, graph_method=None, diffexp_method=None):
+		self.data = _load_data(data)
+
+	@abstractmethod
+	@staticmethod
+	def _load_data(data):
+		pass
+
+	@abstractmethod
+	def cells(self):
+		pass
+
+	@abstractmethod
+	def cellids(self):
+		pass
+
+	@abstractmethod
+	def genes(self):
+		pass
+
+	@abstractmethod
+	def filter_cells(self, filter):
+		"""
+		Filter cells from data and return a subset of the data
+		:param filter:
+		:return: iterator through cells
+		"""
+		pass
+
+	@abstractmethod
+	def metadata_ranges(self, cells_iterator):
+		"""
+		"""
+		pass
+
+	@abstractmethod
+	def metadata(self, cells_iterator):
+		"""
+		"""
+		pass
+
+	@abstractmethod
+	def create_graph(self, cells_iterator):
+		"""
+		"""
+		pass
+
+
+	@abstractmethod
+	def diffexp(self, cells_iterator):
+		"""
+		"""
+		pass