Improves the examples so they're fully runnable

We still need to add READMEs

burr/integrations/streamlit.py

@@ -55,9 +55,11 @@ def prior_actions(self) -> List[str]:
         return out
 
     @property
-    def next_action(self) -> str:
+    def next_action(self) -> Optional[str]:
         if self.display_index < len(self.history) - 1:
             return self.history[self.display_index + 1].action
+        if self.app.get_next_action() is None:
+            return None
         return self.app.get_next_action().name  # return the future one
 
     @property
@@ -122,9 +124,11 @@ def lighten_color(color, amount=0.5):
         lightened_color = colorsys.hls_to_rgb(c[0], 1 - amount * (1 - c[1]), c[2])
         return mc.to_hex(lightened_color)
 
+    seen = {current_node}
     digraph.node(current_node, fillcolor="darkgreen", style="rounded,filled", fontcolor="white")
-    digraph.node(next_node, fillcolor="blue", style="rounded,filled", fontcolor="white")
-    seen = {current_node, next_node}
+    if next_node is not None:
+        digraph.node(next_node, fillcolor="blue", style="rounded,filled", fontcolor="white")
+        seen.add(next_node)
     base_color = "lightblue"
     for i, node in enumerate(prior_nodes):
         if node not in seen:
@@ -272,7 +276,7 @@ def stringify(i):
         # TODO -- consider a callback here instead
         app_state.display_index = current_node_index
 
-    with placeholder.container(height=800):
+    with placeholder.container(height=900):
         state_machine_view, step_view, data_view = st.tabs(
             ["Application", "Action", "State/Results"]
         )

examples/counter/streamlit_app.py

@@ -1,4 +1,4 @@
-import counter
+import application as counter
 import streamlit as st
 
 from burr.integrations.streamlit import (
@@ -36,16 +36,28 @@ def retrieve_state():
 
 def main():
     st.set_page_config(layout="wide")
-    st.title("Counting numbers with Burr")
-    app_state = retrieve_state()  # retrieve first so we can use for the ret of the step
-    columns = st.columns(2)
-    with columns[0]:
+    sidebar = st.sidebar
+    with sidebar:
+        st.markdown(
+            """
+            <style>
+                section[data-testid="stSidebar"] {
+                    width: 400px !important; # Set the width to your desired value
+                }
+            </style>
+            """,
+            unsafe_allow_html=True,
+        )
+        st.title("Counting numbers with Burr")
         st.write(
             "This is a simple counter app. It counts to 10, then loops back to 0. You can reset it at any time. "
             "While we know that this is easy to do with a simple loop + streamlit, it highlights the state that Burr manages."
             "Use the slider to rewind/see what happened in the past, and the visualizations to understand how we navigate "
             "through the state machine!"
         )
+    app_state = retrieve_state()  # retrieve first so we can use for the ret of the step
+    columns = st.columns(2)
+    with columns[0]:
         counter_view(app_state)
         with st.container(height=800):
             md_lines = []