There is an lstrip method just for that:

str.lstrip([chars])

Return a copy of the string with leading characters removed. The chars argument is a string specifying the set of characters to be removed.

'/test/test.json'.lstrip('/')

Ouput:

'test/test.json'

string replace() function perfectly solves this problem:

string.replace(s, old, new[, maxreplace])

Return a copy of string s with all occurrences of substring old replaced by new. If the optional argument maxreplace is given, the first maxreplace occurrences are replaced.

>>> u'longlongTESTstringTEST'.replace('TEST', '?', 1)
u'longlong?stringTEST'

As mentioned in the comments, obj is a dict. One way to replace N/A with Not Applicable regardless of location is to convert it to a string, use string.replace and convert it back to dict for further processing

import json

#Original dict with N/A
obj = {'id': 'fab779b7-2586-4895-9f3b-c9518f34e028', 'project_id': 'a1a73e68-9943-4584-9d59-cc84a0d3e92b', 'created_at': '2017-10-23 02:57:03 -0700', 'sections': [{'section_name': '', 'items': [{'id': 'ffadc652-dd36-4b9f-817c-6539a4b462ab', 'created_at': '2017-10-23 03:36:13 -0700', 'updated_at': '2017-10-23 03:38:32 -0700', 'created_by': 'paul', 'question_text': 'Drawing Ref(s)', 'spec_ref': '', 'display_number': None, 'response': '', 'comment': 'see attached mh309', 'position': 1, 'is_conforming': 'N/A', 'display_type': 'text'}]}]}

#Convert to string and replace
obj_str = json.dumps(obj).replace('N/A', 'Not Applicable')

#Get obj back with replacement
obj = json.loads(obj_str)

The replace function by default is replacing all the occurrences of 1 in the string. You can limit this using the correct syntax as below

Syntax

string.replace(oldvalue, newvalue, count)

If you want only the first occurrence to get replaced you should use

s=s.replace(s[0],'9',1)

text = text.replace("very", "not very", 1)

>>> help(str.replace)
Help on method_descriptor:

replace(...)
    S.replace (old, new[, count]) -> string

    Return a copy of string S with all occurrences of substring
    old replaced by new.  If the optional argument count is
    given, only the first count occurrences are replaced.

You need to call str.replace() with maxreplace parameter. For just replacing the first character in the string, you need to pass maxreplace as 1. For example:

>>> s = "Python is programming language"
>>> s.replace('n', 'o', 1)
'Pythoo is programming language'
#     ^ Here first "n" is replaced with "o"

From the str.replace document:

string.replace(s, old, new[, maxreplace])

Return a copy of string s with all occurrences of substring old replaced by new. If the optional argument maxreplace is given, the first maxreplace occurrences are replaced.

There's json module in python's standard library, it'll be much more error proof to use it rather than replacing strings.

To load json file:

import json
with open("add.json", "r") as fout2:
    json_data = json.load(fout2)
    for change in json_data["Changes"]:
        # strip the contents of trailing white spaces (new line)
        change["Name"] = change["Name"].strip()

# dump json to another file
with open("out.json", "w") as fout:
    fout.write(json.dumps(json_data))

I guess you got the idea. json module will take care that your json data are not corrupted (or at least it'll fail with exception when that occurs).

I would do a regex replacement on the following pattern:

@(@*)

And then just replace with the first capture group, which is all continous @ symbols, minus one.

This should capture every @ occurring at the start of each word, be that word at the beginning, middle, or end of the string.

inp = "hello @jon i am @@here or @@@there and want some@thing in '@here"
out = re.sub(r"@(@*)", '\\1', inp)
print(out)

This prints:

hello jon i am @here or @@there and want something in 'here