I think you are using the wrong tutorial. Not that it matters in this case, but you are linking to the introduction for Python 3.4.
Your mistake is that you dont indent your code after def graphRawFX():
Try this instead:
import matplotlib
import matplotlib.pyplot as plt
import matplotlib.ticker as mticker
import matplotlib.dates as mdates
import numpy as np
def graphRawFX () :
date,bid,ask = np.loadtxt('GPBUSD1d.txt'), unpack=True,
delimiter=',',
converters={0:mdates.strpdate2num('%Y%m%d%H%M%S') }
fig = plt.figure(figsize=(10,7))
ax1 = plt.subplot2grid((40,40), (0,0), rowspan=40, colspan=40)
ax1.plot(date,bid)
ax1.plot(date,ask)
ax1.xaxis.set_major_formatter(mdates.DateFormatter('%Y-%m-%d %H:%M:%S'))
Note: I believe the number of spaces / tabs you are indenting is irrelevant as long as it is the same for each block, but I'm not quite sure.