refactor: simplify conditional logic

Command: `sourcery review --fix --enable de-morgan .`
diff --git a/erpnext/__init__.py b/erpnext/__init__.py
index 5c58f84..48ebe92 100644
--- a/erpnext/__init__.py
+++ b/erpnext/__init__.py
@@ -36,7 +36,7 @@
 
 	if not frappe.flags.company_cost_center:
 		frappe.flags.company_cost_center = {}
-	if not company in frappe.flags.company_cost_center:
+	if company not in frappe.flags.company_cost_center:
 		frappe.flags.company_cost_center[company] = frappe.get_cached_value(
 			"Company", company, "cost_center"
 		)
@@ -47,7 +47,7 @@
 	"""Returns the default company currency"""
 	if not frappe.flags.company_currency:
 		frappe.flags.company_currency = {}
-	if not company in frappe.flags.company_currency:
+	if company not in frappe.flags.company_currency:
 		frappe.flags.company_currency[company] = frappe.db.get_value(
 			"Company", company, "default_currency", cache=True
 		)
@@ -81,7 +81,7 @@
 	if not hasattr(frappe.local, "enable_perpetual_inventory"):
 		frappe.local.enable_perpetual_inventory = {}
 
-	if not company in frappe.local.enable_perpetual_inventory:
+	if company not in frappe.local.enable_perpetual_inventory:
 		frappe.local.enable_perpetual_inventory[company] = (
 			frappe.get_cached_value("Company", company, "enable_perpetual_inventory") or 0
 		)
@@ -96,7 +96,7 @@
 	if not hasattr(frappe.local, "default_finance_book"):
 		frappe.local.default_finance_book = {}
 
-	if not company in frappe.local.default_finance_book:
+	if company not in frappe.local.default_finance_book:
 		frappe.local.default_finance_book[company] = frappe.get_cached_value(
 			"Company", company, "default_finance_book"
 		)
@@ -108,7 +108,7 @@
 	if not hasattr(frappe.local, "party_account_types"):
 		frappe.local.party_account_types = {}
 
-	if not party_type in frappe.local.party_account_types:
+	if party_type not in frappe.local.party_account_types:
 		frappe.local.party_account_types[party_type] = (
 			frappe.db.get_value("Party Type", party_type, "account_type") or ""
 		)