<｜begin▁of▁sentence｜>### Instruction:
As a network analyst working on a research project, you need to query the igraph library to obtain the list of successor vertices for a specific protein molecule within a biochemical network. This will enable you to analyze the influence of the protein molecule on downstream biochemical processes and interactions.
### Response:
import igraph as ig

# Create a simple directed graph
g = ig.Graph([(0, 1), (0, 2), (1, 2), (2, 3)], directed=True)

# Get the vertex object for the first vertex
g_v = g.vs[0]

# Get the successors of the first vertex via the proxy method
successors = g_v.successors()

# Print the successor vertex IDs
print('Vertex 0 successors:', [v.index for v in successors])
<|EOT|>
